Methods of increasing the volume of a perforation tunnel using a shaped charge

ABSTRACT

A method of increasing the volume of a perforation tunnel in a subterranean formation comprises: positioning a shaped charge in a well, wherein the shaped charge comprises a main explosive load, wherein the main explosive load comprises a substance, wherein the substance is capable of increasing the volume of the perforation tunnel whereas a substantially identical shaped charge without the substance is not capable of increasing the volume of the perforation tunnel.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to PCT Application No. PCT/US12/57494,filed on Sep. 27, 2012.

TECHNICAL FIELD

The present invention relates to an improved shaped charge for use inperforating a subterranean formation. Specifically, the shaped chargeincludes a main explosive load, which includes a substance that iscapable of increasing the volume of the perforation tunnel. The increasein volume can be achieved via an increase in the heat of explosion ofthe explosive load. The increase in heat of the explosion can be causedby the substance.

SUMMARY

According to an embodiment, a method of increasing the volume of aperforation tunnel in a subterranean formation comprises: positioning ashaped charge in a well, wherein the shaped charge comprises a mainexplosive load, wherein the main explosive load comprises a substance,wherein the substance is capable of increasing the volume of theperforation tunnel whereas a substantially identical shaped chargewithout the substance is not capable of increasing the volume of theperforation tunnel.

BRIEF DESCRIPTION OF THE FIGURES

The features and advantages of certain embodiments will be more readilyappreciated when considered in conjunction with the accompanyingfigures. The figures are not to be construed as limiting any of thepreferred embodiments.

FIG. 1 depicts a wellbore comprising a shaped charge.

FIG. 2 depicts the shaped charge.

FIG. 3 depicts a perforation tunnel of FIG. 1.

DETAILED DESCRIPTION

As used herein, the words “comprise,” “have,” “include,” and allgrammatical variations thereof are each intended to have an open,non-limiting meaning that does not exclude additional elements or steps.

As used herein, the word “substance” means elements, compositions ormixtures having a definite composition and properties. A substance isintended to include, for example, pure elements, alloys, metals,polymers, compounds, mixtures, and combinations thereof. No compound,mixture, or other material is intended to be excluded by the use of theword “substance.”

Shaped charges are used in a variety of applications, such as militaryand non-military applications. In non-military applications, shapedcharges are used: in the demolition of buildings and structures; forcutting through metal piles, columns and beams; for boring holes; and insteelmaking, quarrying, breaking up ice, breaking log jams, fellingtrees, and drilling post holes. Another common non-military applicationis the oil and gas industry.

Oil and gas hydrocarbons are naturally occurring in some subterraneanformations. A subterranean formation containing oil or gas is sometimesreferred to as a reservoir. A reservoir may be located under land or offshore. Reservoirs are typically located in the range of a few hundredfeet (shallow reservoirs) to a few tens of thousands of feet (ultra-deepreservoirs). In order to produce oil or gas, a wellbore is drilled intoa reservoir or adjacent to a reservoir.

A well can include, without limitation, an oil, gas, or water productionwell, or an injection well. As used herein, a “well” includes at leastone wellbore. A wellbore can include vertical, inclined, and horizontalportions, and it can be straight, curved, or branched. As used herein,the term “wellbore” includes any cased, and any uncased, open-holeportion of the wellbore. A near-wellbore region is the subterraneanmaterial and rock of the subterranean formation surrounding thewellbore. As used herein, a “well” also includes the near-wellboreregion. The near-wellbore region is generally considered to be theregion within approximately 100 feet of the wellbore. As used herein,“into a well” means and includes into any portion of the well, includinginto the wellbore or into the near-wellbore region via the wellbore.

A portion of a wellbore may be an open hole or cased hole. In anopen-hole wellbore portion, a tubing string may be placed into thewellbore. The tubing string allows fluids to be introduced into orflowed from a remote portion of the wellbore. In a cased-hole wellboreportion, a casing is placed into the wellbore that can also contain atubing string. A wellbore can contain an annulus. Examples of an annulusinclude, but are not limited to: the space between the wellbore and theoutside of a tubing string in an open-hole wellbore; the space betweenthe wellbore and the outside of a casing in a cased-hole wellbore; andthe space between the inside of a casing and the outside of a tubingstring in a cased-hole wellbore.

Stimulation techniques can be used to help increase or restore oil, gas,or water production of a well. One example of a stimulation technique isa perforation of a well by using shaped charges. The shaped charges canbe detonated, thereby creating a void that extends into the formation.The void is called a perforation tunnel. The perforation tunnelincreases the permeability of the formation. Permeability refers to howeasily fluids flow through a material. This increase in permeabilitymeans that fluids will flow more easily into or from the wellbore;thereby increasing the overall production of the well and recovery overtime. The perforation tunnels may also allow fracturing fluids to accessthe formation more easily.

In hydraulic fracturing, a fracturing fluid is pumped at a sufficientlyhigh flow rate and high pressure through the wellbore and into the nearwellbore region to create or enhance a fracture in the subterraneanformation. Creating a fracture means making a new fracture in theformation. Enhancing a fracture means enlarging a pre-existing fractureor fissure in the formation. A frac pump is used to pump the fracturingfluid into the wellbore and formation at high rates and pressures, forexample, at a flow rate in excess of 10 barrels per minute (4,200 U.S.gallons per minute) at a pressure in excess of 5,000 pounds per squareinch (“psi”). The pressurized fluid enters the wellbore and formation,through the perforation tunnels. The pressure that is created causes theformation to fracture or crack beyond the perforation tunnels. Thefractures create new channels in the formation which may increase theextraction rate of a well.

Perforation tunnels are often created with the use of shaped charges. Ashaped charge generally includes a conically-shaped charge case, a solidexplosive load, a liner, a central booster, array of boosters, ordetonation wave guide, and a hollow cavity forming the shaped charge. Ifthe hollow cavity is lined with a thin layer of metal, plastic, ceramic,or similar materials, the liner forms a jet when the explosive charge isdetonated. Upon initiation, a spherical wave propagates outward from thepoint of initiation in the basic case of a single point initiatedcharge, initiated along the axis of symmetry. This high pressure wavemoves at a very high velocity, typically around 8 kilometers per second(km/s). As the detonation wave engulfs the lined cavity, the linermaterial is accelerated under the high detonation pressure, collapsingthe liner. During this process, for a typical conical liner, the linermaterial is driven to very violent distortions over very short timeintervals (microseconds) at strain rates of 104 to 107/s. Maximumstrains greater than 10 can be readily achieved since superimposed onthe deformation are very large hydrostatic pressures (peak pressures ofapproximately 200 gigapascals “GPa” (30 million pounds force per squareinch “psi”), decaying to an average of approximately 20 GPa). Thecollapse of the liner material on the centerline forces a portion of theliner to flow in the form of a jet where the jet tip velocity can travelin excess of 10 km/s. The conical liner collapses progressively fromapex to base under point initiation of the high explosive. A portion ofthe liner flows into a compact slug (sometimes called a carrot), whichis the large massive portion at the rear of the jet.

Liners can be made from a variety of materials, including various metalsand glass. Common metals include copper, aluminum, tungsten, tantalum,depleted uranium, lead, tin, cadmium, cobalt, magnesium, titanium, zinc,zirconium, molybdenum, beryllium, nickel, silver, gold, platinum, andpseudo-alloys of tungsten filler and copper binder. The selection of thematerial depends on many factors including economic drivers as well asperformance requirements. For example, a copper and lead powdered matrixpressed into a final geometric form has been found to work well for theoil and gas industry, historically with higher performance embodimentscomprising increasing amounts of tungsten powder within the metalmatrix.

Shaped charges are generally positioned in the wellbore and can beincluded in a perforating gun. The perforating gun can be used to holdthe charges. The perforating gun may be placed inside a casing and islowered into the well on either tubing or a wire line until it is at thedesired location within the well. The perforating gun assembly generallyincludes a charge holder that holds the shaped charges, a detonationcord that links each charge located in the charge holder, and adetonator. When the charges are detonated, particles are expelled,forming a high-velocity jet that creates a pressure wave that exertspressure on the formation and possibly the casing for a cased-holeportion. The detonation creates the perforation tunnel by forcingmaterial radially away from the jet axis.

It has been discovered that the volume of a perforation tunnel can beincreased by using a shaped charge including a substance within the mainexplosive load. The substance increases the overall heat produced by thedetonation or explosion of the charge. The increased heat of explosionwill result in an increase in volume of the perforation tunnel.

According to an embodiment, a method of increasing the volume of aperforation tunnel in a subterranean formation comprises: positioning ashaped charge in a well, wherein the shaped charge comprises a mainexplosive load, wherein the main explosive load comprises a substance,wherein the substance is capable of increasing the volume of theperforation tunnel whereas a substantially identical shaped chargewithout the substance is not capable of increasing the volume of theperforation tunnel.

Any discussion of the embodiments regarding the shaped charge isintended to apply to all of the method embodiments. Any discussion of aparticular component of an embodiment (e.g., a shaped charge or asubstance) is meant to include the singular form of the component andalso the plural form of the component, without the need to continuallyrefer to the component in both the singular and plural form throughout.For example, if a discussion involves “the shaped charge 100,” it is tobe understood that the discussion pertains to one shaped charge(singular) and two or more shaped charges (plural).

Turning to the Figures, FIG. 1 depicts a well system 10 containingmultiple shaped charges 100 located within multiple zones of the wellsystem. The well system 10 can include at least one wellbore 11. Thewellbore 11 can penetrate a subterranean formation 20. The subterraneanformation 20 can be a portion of a reservoir or adjacent to a reservoir.The wellbore 11 can have a generally vertical cased or uncased section14 extending downwardly from a casing 15, as well as a generallyhorizontal cased or uncased section extending through the subterraneanformation 20. The wellbore 11 can include only a generally verticalwellbore section or can include only a generally horizontal wellboresection.

A tubing string 24 (such as a stimulation tubing string or coiledtubing) can be installed in the wellbore 11. The well system 10 cancomprise at least a first zone 16 and a second zone 17. The well system10 can also include more than two zones, for example, the well system 10can further include a third zone 18, a fourth zone 19, and so on. Themethods include the step of positioning a shaped charge 100 in a well.More than one shaped charge 100 can be positioned in the well. Accordingto an embodiment, a first shaped charge can be positioned within thefirst zone 16, a second shaped charge can be positioned within thesecond zone 17, and so on. It is to be understood that more than oneshaped charge can be positioned within a given zone (e.g., the firstzone or second zone). According to an embodiment, the well system 10includes anywhere from 2 to hundreds or thousands of zones. The zonescan be isolated from one another in a variety of ways known to thoseskilled in the art. For example, the zones can be isolated via multiplepackers 26. The packers 26 can seal off an annulus located between theoutside of the tubing string 24 and the wall of wellbore 11.

It should be noted that the well system 10 is illustrated in thedrawings and is described herein as merely one example of a wide varietyof well systems in which the principles of this disclosure can beutilized. It should be clearly understood that the principles of thisdisclosure are not limited to any of the details of the well system 10,or components thereof, depicted in the drawings or described herein.Furthermore, the well system 10 can include other components notdepicted in the drawing. For example, the well system 10 can furtherinclude a well screen. By way of another example, cement may be usedinstead of packers 26 to isolate different zones. Cement may also beused in addition to packers 26.

The well system 10 does not need to include a packer 26. Also, it is notnecessary for one well screen and one shaped charge 100 to be positionedbetween each adjacent pair of the packers 26. It is also not necessaryfor a single shaped charge 100 to be used in conjunction with a singlewell screen. Any number, arrangement and/or combination of thesecomponents may be used.

The step of positioning can comprise inserting the shaped charge 100into the well. The shaped charge 100 can be positioned in the well at adesired location. According to an embodiment, the desired location isthe location at which the perforation tunnel 22 is to be created. Theshaped charge 100 can be included in a carrier (not shown). More thanone shaped charge 100 can be included in the carrier. The carrier can beany carrier capable of holding the shaped charge 100, for example, thecarrier can be a perforating gun. The step of positioning can furthercomprise inserting the carrier into the well. The methods can furtherinclude the step of inserting the shaped charge 100 into the carrier,wherein the step of inserting is performed prior to the step ofpositioning.

As can be seen in FIG. 2, the shaped charge 100 includes a mainexplosive load 102. The shaped charge 100 can further include a chargecase 101, wherein the charge case 101 is positioned adjacent to the mainexplosive load 102. The charge case 101 can comprise a metal or metalalloy. As used herein, the term “metal alloy” means a mixture of two ormore elements, wherein at least one of the elements is a metal. Theother element(s) can be a non-metal or a different metal. An example ofa metal and non-metal alloy is steel, comprising the metal element ironand the non-metal element carbon. An example of a metal and metal alloyis bronze, comprising the metallic elements copper and tin. The metal ormetal alloy of the charge case 101 can be selected from the groupconsisting of aluminum, zinc, magnesium, titanium, tantalum, andcombinations thereof.

The shaped charge 100 can further comprise a liner 103, wherein theliner 103 is positioned adjacent to the main explosive load 102. As canbe seen in FIG. 2, the shaped charge 100 can include a liner 103, themain explosive load 102, and a charge case 101, wherein the liner 103 ispositioned adjacent to the main explosive load 102 and the charge case101 is positioned adjacent to the other side of the main explosive load102. The liner 103 can be made from a variety of materials, includingvarious metals and glass. Common metals include copper, aluminum,tungsten, tantalum, depleted uranium, lead, tin, cadmium, cobalt,magnesium, titanium, zinc, zirconium, molybdenum, beryllium, nickel,silver, gold, platinum, and pseudo-alloys of tungsten filler and copperbinder. The liner 103 can have a thickness of at least 0.025 inches(in). According to another embodiment, the liner 103 has a thickness inthe range of about 0.025 to about 0.250 in, preferably of about 0.050 toabout 0.100 in.

The shaped charge 100 can further comprise a central booster, array ofboosters, or detonation wave guide (shown in FIG. 2 as a central booster106). According to an embodiment, the central booster, array ofboosters, or detonation wave guide is capable of detonating the mainexplosive load 102. Detonation means a supersonic exothermic frontaccelerating through a medium that eventually drives a shock front orwave that propagates directly in front of the explosive load. The shapedcharge 100 can further include a seal disc 105 and a detonation cord104. According to an embodiment, the detonation cord 104 is capable ofinitiating the central booster, array of boosters, detonation waveguide, or the main explosive load 102. If more than one shaped charge100 is positioned in the well, then the detonation cord 104 can beconnected to and link two or more of the shaped charges 100 together.The detonation cord 104 can be part of a carrier (not shown).

The shaped charge 100 comprises the main explosive load 102. Accordingto an embodiment, the main explosive load 102 comprises an explosivematerial. The explosive material can be selected fromcommercially-available materials. For example, the explosive materialcan be selected from the group consisting of[3-Nitrooxy-2,2-bis(nitrooxymethyl)propyl]nitrate “PETN”;1,3,5-Trinitroperhydro-1,3,5-triazine “RDX”;Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine “HMX”;1,3,5-Trinitro-2-[2-(2,4,6-trinitrophenyl)ethenyl]benzene “HNS”;2,6-bis,bis(picrylamino)-3,5-dinitropyridine “PYX”;1,3,5-trinitro-2,4,6-tripicrylbenzene “BRX”;2,2′,2″,4,4′,4″,6,6′,6″-nonanitro-m-terphenyl “NONA”; and combinationsthereof. According to an embodiment, the main explosive load 102 furthercomprises a de-sensitizing material. The de-sensitizing material can becapable of binding the main explosive load 102 together. Thede-sensitizing material can also help the main explosive load 102 retainits shape. The de-sensitizing material can be selected from the groupconsisting of a wax, graphite, plastics, thermoplastics, fluoropolymers(e.g., polytetrafluoroethylene), other non-energetic (inert) binders,and combinations thereof.

The substance is capable of increasing the volume of the perforationtunnel 22; whereas, a substantially identical shaped charge without thesubstance is not capable of increasing the volume of the perforationtunnel. As used herein, the phrase “substantially identical” means thedevice contains the same components, materials, concentrations ofmaterials, etc. with the exception of the component or materialspecifically excluded. As can be seen in FIG. 3, the perforation tunnel22 can be, but is not limited to being, conical in shape. The increasein volume can be an increase in at least one dimension of theperforation tunnel. According to an embodiment, the increase in the atleast one dimension can be an increase in the diameter of the base ofthe perforation tunnel b, the length of the perforation tunnel l, anincrease in both the diameter of the base b and the length l, or anincrease in a diameter at any interval along the length l. The increasein the volume can vary depending on the specifics of the oil or gasoperation. The increase in the volume can be a desired value.

According to an embodiment, the substance is capable of increasing thevolume of the perforation tunnel 22 via an increase in the amount ofheat of explosion of the main explosive load 102 (i.e., the amount ofheat produced during detonation of the main explosive load). Thegeneration of heat in large quantities accompanies most explosivechemical reactions. It is the rapid liberation of heat that causes thegaseous products of most explosive reactions to expand and generate highpressures. This rapid generation of high pressures of the released gasconstitutes the explosion. The strength, or potential, of an explosiveis the total work that can be performed by the gas resulting from itsexplosion, when expanded adiabatically from its original volume, untilits pressure is reduced to atmospheric pressure and its temperature to15° C. The potential is therefore the total quantity of heat given offat constant volume when expressed in equivalent work units and is ameasure of the strength of the explosive. Each product and reactantmaking up the explosive load will have a specific heat of formation. Thestandard heat of formation of a compound is the change of enthalpy thataccompanies the formation of 1 mole of the compound from its elements,with all substances being in their standard states. The heat released bythe explosive material at a constant pressure and 25° C. can becalculated as follows:

HEX=ΔU=|U _(prod1) −U _(react1) |+|U _(prod2) −U _(react2)| . . . ,

where HEX refers to the heat of explosion in units of calories per gram(cal/g); ΔU is the change in energy at a constant volume for thecalorimetric reaction; and U_(prod) and U_(react) are the internalenergies of the products and reactants (1, 2, and so on), respectively,at room temperature (i.e., 25° C. (298.15 K)). The heat released can bereferred to as the “heat of explosion.” With an increase in HEX, theexplosive load has an increased ability to do work. This increasedability to do work means that the overall volume of the perforationtunnel can be increased compared to an explosive load without theincrease in HEX. According to an embodiment, the increase in the heat ofexplosion is predetermined. The predetermined heat of explosion can, inpart, be calculated based on the desired increase in the volume of theperforation tunnel 22, but may also be derived from experimentalresults.

According to an embodiment, the substance is any substance that iscapable of increasing the overall heat of explosion of the mainexplosive load 102, thereby resulting in an overall increase in theability to perform work, thereby increasing the perforation tunnelgeometry. The main explosive load 102 can also comprise more than onesubstance. The substance can be selected from the group consisting ofmetals, metal alloys, plastics, thermoplastics, fluoropolymers (e.g.,polytetrafluoroethylene), and combinations thereof. The metal or metalalloy can be selected from (but not limited to) the group consisting ofaluminum, zinc, magnesium, titanium, tantalum, and combinations thereof.The quantity of the heat of explosion and overall higher work energy canvary and will depend on the heat for formation of the specificsubstance(s) chosen. For example, the heat of formation of aluminumoxide (Al₂O) is 163 kilojoules per mole (kJ/mol) and the heat offormation of aluminum III oxide (Al₂O₃) is 1,590 kJ/mol. According to anembodiment, the one or more substances are chosen such that a desiredheat of explosion is achieved.

The quantity of the heat of explosion can also depend on theconcentration of the one or more substances. Generally, the greater theconcentration of the substance, the greater the heat of explosion.According to an embodiment, the concentration of the one or moresubstances is selected such that the desired heat of explosion isachieved. According to another embodiment, the concentration of the oneor more substances is selected such that the desired increase in volumeof the perforation tunnel is achieved. According to yet anotherembodiment, the substance is in a concentration of at least 0.05% byweight of the main explosive load 102. According to yet anotherembodiment, the substance is in a concentration in the range of about0.05% to about 40%, preferably about 1% to about 25%, by weight of themain explosive load 102.

The heat of explosion can be limited by the oxygen balance of theexplosive. Oxygen balance (OB or OB %) indicates the degree to which anexplosive can be oxidized. If an explosive molecule contains just enoughoxygen to form carbon dioxide from carbon, water from hydrogenmolecules, all of its sulfur dioxide from sulfur, and all metal oxidesfrom metals with no excess molecules, then the explosive has a zerooxygen balance. An explosive has a positive oxygen balance if theexplosive contains more oxygen than needed, and an explosive has anegative oxygen balance if the explosive contains less oxygen thanneeded. If the explosive has a negative oxygen balance, then thecombustion of the explosive molecules will be incomplete, and largeamounts of toxic gases such as carbon monoxide will be present.Generally, when a positive or zero OB is present, the heat of explosionwill be the greatest; whereas, the heat of explosion will be less when anegative OB is present. According to an embodiment, the main explosiveload 102 has a positive or zero OB. According to another embodiment, asufficient amount of oxygen (O₂) is available to cause completecombustion of the main explosive load 102. The available O₂ can comefrom the substance, part of another material (e.g., the booster), and/orthe area surrounding the shaped charge.

The substance can be selected such that at least a sufficient amount ofoxygen is available in order to achieve complete combustion of the mainexplosive load 102. The substance can also be selected such that atleast a sufficient amount of oxygen is available in order to achieve thepredetermined heat of explosion. The substance can also be selected suchthat at least a sufficient amount of oxygen is available in order toachieve the desired increase in volume of the perforation tunnel 22. Theconcentration of the substance can also be selected such that at least asufficient amount of oxygen is available in order to achieve completecombustion of the main explosive load; alternatively, such that at leasta sufficient amount of oxygen is available in order to achieve thepredetermined heat of explosion; alternatively, such that the desiredincrease in volume of the perforation tunnel is achieved. By way ofexample, Al₂O₃ can provide more available oxygen compared to Al₂O. Thesubstance and/or the concentration of the substance can also be selectedbased on the quantity of available oxygen present in the areasurrounding the positioned shaped charge.

The substance can also form available oxygen by reacting with otherunoxidized elements or compounds present in the system. The substancecan also increase the heat of explosion by reacting with otherunoxidized elements or compounds present in the system. By way ofexample, if the substance is Al₂O and a negative OB is present, then theformation of Al₂O₃ via a reaction of the Al₂O and other unoxidizedcompounds or elements can occur. The formation of Al₂O₃ is a highlyexothermic chemical reaction and can increase the overall heat ofexplosion.

The methods can further comprise the step of detonating the mainexplosive load 102, wherein the step of detonating is performed afterthe step of positioning. The step of detonating can comprise causinginitiation of the main explosive load 102. The initiation of the mainexplosive load 102 can include initiating the booster 106, boosterarray, or detonation wave guide. According to an embodiment, thedetonation of the main explosive load 102, and the jet produced by theliner material 103, creates the resulting perforation tunnel 22. Morethan one main explosive load 102 can be detonated. As can be seen inFIG. 1, a first main explosive load 102 located in the first zone 16 canbe detonated; thereby creating a first perforation tunnel 22, a secondmain explosive load shown located in the third zone 18 can be detonated;thereby creating a second perforation tunnel, and so on. Of course morethan one main explosive load can be detonated within a given zone.Moreover, not every zone need include a shaped charge and the exactzones that contain a shaped charge and the total number of shapedcharges positioned within those zones can vary depending on thespecifics of the particular oil or gas operation.

The methods can further comprise the step of fracturing at least aportion of the subterranean formation 20, wherein the step of fracturingis performed after the step of positioning or after the step ofdetonating. The step of fracturing can include placing a fracturingfluid into at least one of the perforation tunnels 22. The methods canfurther include the step of performing an acidizing treatment in atleast a portion of the subterranean formation 20, wherein the step ofperforming an acidizing treatment is performed after the step ofpositioning or after the step of detonating. The step of performing anacidizing treatment can include introducing an acidizing fluid into atleast one of the perforation tunnels 22.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is, therefore, evident thatthe particular illustrative embodiments disclosed above may be alteredor modified and all such variations are considered within the scope andspirit of the present invention. While compositions and methods aredescribed in terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods also can “consistessentially of” or “consist of” the various components and steps.Whenever a numerical range with a lower limit and an upper limit isdisclosed, any number and any included range falling within the range isspecifically disclosed. In particular, every range of values (of theform, “from about a to about b,” or, equivalently, “from approximately ato b,”) disclosed herein is to be understood to set forth every numberand range encompassed within the broader range of values. Also, theterms in the claims have their plain, ordinary meaning unless otherwiseexplicitly and clearly defined by the patentee. Moreover, the indefinitearticles “a” or “an”, as used in the claims, are defined herein to meanone or more than one of the element that it introduces. If there is anyconflict in the usages of a word or term in this specification and oneor more patent(s) or other documents that may be incorporated herein byreference, the definitions that are consistent with this specificationshould be adopted.

What is claimed is:
 1. A method of increasing the volume of aperforation tunnel in a subterranean formation comprising: positioning ashaped charge in a well, wherein the shaped charge comprises a mainexplosive load, wherein the main explosive load comprises a substance,wherein the substance is capable of increasing the volume of theperforation tunnel whereas a substantially identical shaped chargewithout the substance is not capable of increasing the volume of theperforation tunnel.
 2. The method according to claim 1, wherein the stepof positioning comprises inserting the shaped charge into the well. 3.The method according to claim 1, wherein the main explosive loadcomprises an explosive material.
 4. The method according to claim 3,wherein the explosive material is selected from the group consisting of:[3-Nitrooxy-2,2-bis(nitrooxymethyl)propyl]nitrate “PETN”;1,3,5-Trinitroperhydro-1,3,5-triazine “RDX”;Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine “HMX”;1,3,5-Trinitro-2-[2-(2,4,6-trinitrophenyl)ethenyl]benzene “HNS”;2,6-bis,bis(picrylamino)-3,5-dinitropyridine “PYX”;1,3,5-trinitro-2,4,6-tripicrylbenzene “BRX”;2,2′,2″,4,4′,4″,6,6′,6″-nonanitro-m-terphenyl “NONA”; and combinationsthereof.
 5. The method according to claim 1, wherein the increase involume of the perforation tunnel is an increase in at least onedimension of the perforation tunnel.
 6. The method according to claim 1,wherein the substance is capable of increasing the volume of theperforation tunnel via an increase in the amount of heat of explosion ofthe main explosive load.
 7. The method according to claim 6, wherein thesubstance is any substance that is capable of increasing the heat ofexplosion of the main explosive load.
 8. The method according to claim6, wherein the increase in the heat of explosion is predetermined. 9.The method according to claim 8, wherein the concentration of thesubstance is selected such that the predetermined heat of explosion isachieved.
 10. The method according to claim 8, wherein the substance isselected such that a predetermined heat of explosion is achieved. 11.The method according to claim 1, wherein the main explosive loadcomprises more than one substance.
 12. The method according to claim 1,wherein the substance is selected from the group consisting of metals,metal alloys, plastics, thermoplastics, fluoropolymers, and combinationsthereof.
 13. The method according to claim 10, wherein the metal ormetal alloy is selected from the group consisting of aluminum, zinc,magnesium, titanium, tantalum, and combinations thereof.
 14. The methodaccording to claim 1, wherein the concentration of the substance isselected such that a desired increase in volume of the perforationtunnel is achieved.
 15. The method according to claim 1, wherein thesubstance is in a concentration in the range of about 0.05% to about 40%by weight of the main explosive load.
 16. The method according to claim1, wherein the main explosive load has a positive or zero oxygenbalance.
 17. The method according to claim 1, wherein a sufficientamount of oxygen is available to cause complete combustion of the mainexplosive load.
 18. The method according to claim 1, wherein thesubstance is selected such that at least a sufficient amount of oxygenis available in order to achieve a desired increase in volume of theperforation tunnel.
 19. The method according to claim 1, wherein theconcentration of the substance is selected such that at least asufficient amount of oxygen is available in order to achieve a desiredincrease in volume of the perforation tunnel.
 20. The method accordingto claim 1, further comprising the step of detonating the main explosiveload, wherein the step of detonating is performed after the step ofpositioning.